And examining bug behavior.
The most commonly used knots for this purpose are the blood and double surgeon's knots. Determining which is the best to use is a bit like arguing the merits of Chevy over Ford-it's a personal thing. Ultimately, the best knot to use is the one you can tie the easiest and that has performed the best for you in the past.
Personally, I use a double surgeon's for just about every situation because after 12 years I'm pretty comfortable tying it, but that's just me. I asked a few "pros" what knots they use and this is what we found out. Brian Kimmel, guide, Shadow of a Trout Outfitters in Big Sky, Montana: "I always tie a blood knot. Once you get some muscle memory they are very quick to tie. Day in, day out, it is the most consistently strong knot in my boat." Barry and Cathy Beck, fly-fishing guides and world-traveling photographers: "We have always used the surgeon's knot for attaching tippets to leaders. It's quick, simple and easy to tie after dark when you can't see anymore. We wet it so it sets well and it works with almost any size of monofilament."
Tom Hargrove, owner, T. Hargrove Fly Shop, St. Louis, Missouri: "I am a fan of the blood knot for my tippet-to-leader connections. This is harder to tie but it leaves a nice, clean, tapered knot." Jeremy Gilbertson, guide, Big Sky Fly Fishers of Billings, Montana: "I always use a blood knot. I just never was able to tie a surgeon's knot that'd compare."
To expand things a bit, a loop-to-loop connection (such as two double surgeon's loops joined together) is sometimes used to connect a light tippet to a leader. Brian Kimmel says, "I like to fish a 7-foot, 3X leader and tie a 3-foot piece of light tippet with loops. I get exceptional knot strength and the loop-to-loop works fantastic as a shock absorber."
Ultimately, the answer to this question comes down to personal preference and experience. In either case, it's best to know how to tie all these knots well. For a primer on tying blood and surgeon's knots, check out Buzz Bryson's excellent article in the March 2008 issue of FR&R or see the knot illustrations online at flyrodreel.com in the Skills section.
I've noticed that caddis and mayflies fly upstream after they hatch. Is this a universal behavior?
The standard explanation for the upstream flight of caddis, for instance, is that they fly upstream to lay eggs in the area where they themselves were born. As larvae, the caddis move downstream in what is called "behavioral drift." After the caddis mature while downstream, they emerge as adults and fly upriver to mate and lay eggs.
However, according to Stephen Hiner, an entomologist at Virginia Tech University, one study showed that the direction of caddis flight is nearly equal in either direction, with slightly more heading upriver (and the majority of these being females with eggs). Furthermore, in general, most mayflies do not head upstream; wind is the prime determinant of flight direction for this group or order of insects.
Dr. Frank Carle of Rutgers University has theorized that insect flight was driven by the need for the most ancient winged insects (dragonflies and mayflies) to return to their upstream nursery areas to mate and lay eggs. The constant temperature and chemical make up of these upstream areas were important for the growth of the nymphs, and were probably rarer 400 million years ago than today. -J. R.